Electronic devices such as computers, laptops, personal video recorders (PVRs), MP3 players, game consoles, set-top boxes, digital cameras, and other electronic devices often need to store a large amount of data. Storage devices such as hard disk drives (HDD) may be used to meet these storage requirements. One goal of HDD designers is to reduce data access times, increase storage density and/or reduce power consumption of the HDDs.
Referring now to FIG. 1, an exemplary data storage architecture 10 is shown and includes one or more hard drive platters 14 that are coated with magnetic layers 15. The magnetic layers 15 store positive and negative magnetic fields that represent binary 1's and 0's. A spindle motor, which is shown schematically at 16, rotates the platter 14. Generally the spindle motor 16 rotates the hard drive platter 14 at a fixed speed during read/write operations. One or more read/write actuator arms 18 move relative to the platter 14 to read and/or write data to/from the hard drive platters 14.
A read/write device 20 is located near a distal end of the read/write arm 18. The read/write device 20 includes a write element such as an inductor that generates a magnetic field. The read/write device 20 also includes a read element (such as a magneto-resistive (MR) element) that senses the magnetic field on the platter 14. A preamp circuit 22 amplifies analog read/write signals.
When reading data, the preamp circuit 22 amplifies low level signals from the read element and outputs the amplified signal to a read/write channel device 24. When writing data, a write current is generated which flows through the write element of the read/write device 20. The write current is switched to produce a magnetic field having a positive or negative polarity. The positive or negative polarity is stored by the hard drive platter 14 and is used to represent data.
A buffer 32 stores data that is associated with the control of the hard disk drive and/or buffers data to allow data to be collected and transmitted as larger data blocks to improve efficiency. The buffer 32 may employ SDRAM or other types of low latency memory. A processor 34 performs processing that is related to the operation of the hard disk drive 10. A hard disk controller (HDC) 36 communicates with a host 37 via an input/output (I/O) interface 38. The HDC 36 also communicates with a spindle/voice coil motor (VCM) driver 40 and/or the read/write channel device 24. The I/O interface 38 can be a serial or parallel interface, such as an Integrated Drive Electronics (IDE), Advanced Technology Attachment (ATA), or serial ATA (SATA) interface. The spindle/VCM driver 40 controls the spindle motor 16, which rotates the platter 14. The spindle/VCM driver 40 also generates control signals that position the read/write arm 18, for example using a voice coil actuator, a stepper motor or any other suitable actuator.
Referring now to FIG. 2, the hard drive platter 14 includes a substrate 51 having the magnetic layers 15 that store data in a nonvolatile manner. The magnetic layers 15 are divided into tracks 54, which include concentric circular sections. The tracks 54 are divided radially into sectors. The magnetic layers 15 are typically coated on the substrate 51 using bonding, sintering, electroplating, sputtering, deposition, spraying and/or other techniques. A protective layer (not shown) may also be added to protect the platter 14 from scratches and/or debris.
The substrate 51 is preferably durable, lightweight, inflexible, and heat resistant. The substrate 51 should resist warping due to heat, high rotational speeds and/or vibration during use. The platters 14 are typically constructed from aluminum alloy or glass, although other materials may be used.
If an aluminum alloy platter is constructed too thin, it is susceptible to deformation, which may cause wobbling during rotation. During high-speed rotation, the aluminum alloy platter may expand. Additionally, clamping the aluminum alloy platter to the spindle motor may cause deformation. Referring now to FIGS. 3A and 3B, the hard drive platter 14 is shown to include the substrate 51 and the magnetic layers 15 formed on at least one surface thereof. A central bore 76 receives a clamping device 78, associated with the spindle motor 16. The clamping device 78 may cause the hard drive platter 70 to deform either downwardly (as shown) or upwardly.
Glass hard drive platters are not as susceptible to deformation due to high-speed rotation. Therefore, glass hard drive platters can be thinner and lighter than those constructed from aluminum alloy. As a result, data storage devices that use glass platters may be equipped with a smaller motor that requires less power, and is therefore more efficient. Glass platters, however, are more expensive to manufacture than aluminum alloy platters. Additionally, glass cannot be injection-molded and must be cut, which increases the cost to produce the platters.